1. Field of the Invention
The present invention relates to a film forming apparatus having a plurality of heads, a head cleaning method for cleaning each head, a device manufacturing system for manufacturing a device, and a device manufactured by using the film forming apparatus or by a manufacturing process which includes the head cleaning method. In particular, the present invention relates to a film forming apparatus, a head cleaning method, and a device manufacturing system for reliably cleaning each nozzle face while flexibly coping with changes in specification for a substrate to be manufactured, and relates to devices manufactured using the film forming apparatus, the head cleaning method, and the device manufacturing system.
2. Description of the Related Art
According to recent improvements in various kinds of electronic devices such as computers, portable information devices, and the like, demand and applicable fields for liquid crystal devices, in particular, color liquid crystal devices, have increased. Such liquid crystal devices use a color filter substrate for colorizing the display image. In order to manufacture the color filter substrate, an inkjet method is known, in which color filter elements R (red), G (green), and B (blue) are formed as a specific pattern on the substrate.
In order to implement the inkjet method, an inkjet system having a plurality of inkjet heads for jetting ink droplets has been developed. Each inkjet head has an ink chamber for temporarily storing ink which is supplied from an external device, a pressure generating element (e.g., piezo element) functioning as a driving force for jetting a specific amount of ink stored in the ink chamber, and a nozzle face having an opening (i.e., nozzle) through which each ink droplet is jetted from the ink chamber.
The inkjet heads are arranged at an equivalent pitch so as to form a set of heads, and ink droplets are jetted while the substrate is scanned by the set of heads which is moved in a specific direction (e.g., the X direction), so that R, G, and B inks are supplied to the substrate. On the other hand, the position of the substrate in the Y direction, which is perpendicular to the X direction, is controlled at the side of a stage on which the substrate is placed.
Regarding the substrate to be manufactured (e.g., the color filter substrate), high resolution is required and thus finer patterns should be formed. In consideration of these circumstances, it is necessary for each inkjet head to very accurately supply each ink droplet (of R, G, or B) on a specific area. Therefore, each inkjet head should straightly jet a specific size of ink droplet towards a target point on the substrate. However, if ink remains on the nozzle face, the remaining ink may obstruct desired jetting of ink droplets. Such remaining ink is produced when a portion of an ink droplet adheres to the nozzle face, and it is difficult to completely prevent the occurrence of remaining ink when ink is used.
In order to solve this problem, a cleaning mechanism for wiping remaining ink which is adhered on the nozzle face may be provided for each inkjet head. However, this method causes another problem; that is, it is difficult to flexibly cope with diversified specifications for the substrate, where diversification of the substrate has been accelerated.
That is, when the size of the substrate (e.g., color filter substrate) to be manufactured, the pitch for pixels, or the like is changed in the specification, in the set of the heads, the arrangement pitch between the inkjet heads or the degree of inclination of each inkjet head with respect to the scanning direction can be changed; however, it may also be required to adjust the position of the cleaning mechanism for each inkjet head or to replace all the cleaning mechanisms. Such adjustment imposes a great burden on the worker or operator, and in addition to that, improvement of productivity may be obstructed.